Crowded roadways and packed buses, trains and ferries are on tap for commuters starting Wednesday night, when officials shut down the San Francisco-Oakland Bay Bridge to traffic in preparation for a new $6.4 billion span opening early next week.The California Highway Patrol will begin blocking traffic on and off of the bridge at about 7:30 p.m. Wednesday, rerouting motorists to other freeways, Officer Daniel Hill said.The closure is expected to have region-wide effects on traffic; the Bay Bridge is a workhorse crossing, with about 280,000 vehicles using it each day. This weekend's closure is the fourth time in seven years that officials have shut the bridge down over the Labor Day weekend, when traffic is significantly lighter.The new crossing is expected to open late Monday or early Tuesday morning, but the exact timing is still being worked out, bridge spokesman Andrew Gordon said.It will be nearly 24 years since the 6.9-magnitude Loma Prieta earthquake permanently damaged the existing eastern span, setting off a public works project marked by numerous delays, political fights over its design and complex engineering hurdles.Transportation officials urged people to plan ahead for the closure. BART trains will run 24 hours starting Wednesday night through the holiday weekend. Bus and ferry service will also be bolstered to help people move around."Be patient, wherever you're going," John Goodwin, spokesman for the Metropolitan Transportation Commission, said. "We saw this same thing during the bridge closures in 2007 and 2009. The Bay Area keeps moving. It just becomes more sluggish."Once traffic is stopped over the bridge, construction crews will immediately begin preparing the new single-tower suspension span for its opening late Monday or early Tuesday.All large-scale construction on the new span has been finished, so crews will be working around the clock to prepare the gleaming white span for its opening by striping lanes, adding railing and other final details, Gordon said.Still, many details of the new bridge's opening are still up in the air, including who will be there to cut the chain in the official opening ceremony, currently scheduled for 3 p.m. Monday.Gov. Jerry Brown, who was intimately involved in the bridge's planning as mayor of Oakland, decided to skip the ceremony to instead be with his wife at a family gathering in Michigan.When the new bridge does open, CHP cruisers will lead the first traffic over the span to help moderate speed, Officer Hill said.People planning trips throughout the region over the Labor Day weekend should check 511.org for alternative routes and transportation methods, officials said.

SAN FRANCISCO —

Crowded roadways and packed buses, trains and ferries are on tap for commuters starting Wednesday night, when officials shut down the San Francisco-Oakland Bay Bridge to traffic in preparation for a new $6.4 billion span opening early next week.

The California Highway Patrol will begin blocking traffic on and off of the bridge at about 7:30 p.m. Wednesday, rerouting motorists to other freeways, Officer Daniel Hill said.

The closure is expected to have region-wide effects on traffic; the Bay Bridge is a workhorse crossing, with about 280,000 vehicles using it each day. This weekend's closure is the fourth time in seven years that officials have shut the bridge down over the Labor Day weekend, when traffic is significantly lighter.

The new crossing is expected to open late Monday or early Tuesday morning, but the exact timing is still being worked out, bridge spokesman Andrew Gordon said.

It will be nearly 24 years since the 6.9-magnitude Loma Prieta earthquake permanently damaged the existing eastern span, setting off a public works project marked by numerous delays, political fights over its design and complex engineering hurdles.

Transportation officials urged people to plan ahead for the closure. BART trains will run 24 hours starting Wednesday night through the holiday weekend. Bus and ferry service will also be bolstered to help people move around.

"Be patient, wherever you're going," John Goodwin, spokesman for the Metropolitan Transportation Commission, said. "We saw this same thing during the bridge closures in 2007 and 2009. The Bay Area keeps moving. It just becomes more sluggish."

Once traffic is stopped over the bridge, construction crews will immediately begin preparing the new single-tower suspension span for its opening late Monday or early Tuesday.

All large-scale construction on the new span has been finished, so crews will be working around the clock to prepare the gleaming white span for its opening by striping lanes, adding railing and other final details, Gordon said.

Still, many details of the new bridge's opening are still up in the air, including who will be there to cut the chain in the official opening ceremony, currently scheduled for 3 p.m. Monday.

Gov. Jerry Brown, who was intimately involved in the bridge's planning as mayor of Oakland, decided to skip the ceremony to instead be with his wife at a family gathering in Michigan.

When the new bridge does open, CHP cruisers will lead the first traffic over the span to help moderate speed, Officer Hill said.

People planning trips throughout the region over the Labor Day weekend should check 511.org for alternative routes and transportation methods, officials said.